The present invention relates to mowing machines of the type having a cutting assembly rotatable in a cutting plane and more particularly to a rotary disk-like casing containing therein at least one flatly coiled cutting line made of a high polymer synthetic material.
The field of technology to which the present invention is directed is mowing apparatus of a type wherein a rotary assembly is provided with at least one nonmetallic flexible line wound about a spool, the effective working length of the line being adapted to be lengthened at desired times while it is in a non-working condition, as the working length becomes shortened during use. Nylon monofilament strings which are almost completely incapable of causing any significant injury to persons or animals struck by the flailing cutting string are effective for use as safe, rotary cutting means. These strings are particularly suitable for cutting or trimming along fences, walls and the trunks or stems of trees.
There is illustrated and described in U.S. Pat. Nos. 3,708,967; 3,826,068; and 3,859,776 one or more embodiments of a mowing device having a rotary head member arranged to be rotated by a gasoline-powered engine or electric motor together with one or more spools which is housed in lockable relation to the rotary head member. A length of flexible nonmetallic line is coiled about the spool and its free end extends peripherally from the spool and the head. The free end swings arcuately about upon the actuation of the engine or motor to cut adjacent vegetation in the manner of a flail. The line storage means in the form of spools is locked from rotation but is releasable so that additional line may be payed out as the effective working length of the line becomes shortened during use.
However, the aforementioned device is subject to certain disadvantages due to having the storage means in the form of spools. One of the disadvantages is that the rotary head must be high so as to accommodate the vertical length of the spool. Also, the rotary head is complicated in order to provide a means for locking and releasing the spool. Another inconvenience is that the outermost layer is likely to become slack with the result that the free end will unwind more than is necessary to produce an effective working length to be payed out. This results in the troublesome job of rearranging the line and the spool. This problem occurs when the spool is stored, when an additional length is drawn, and when the device starts or stops to rotate. Accordingly, there is a demand for improved mowing apparatus which is free from the aforementioned disadvantages.
Therefore, it is an object of the present invention to provide an improved mowing apparatus having storage means in the form of a hollow disk which contains at least one flatly coiled and radially interconnected cutting string made of a high polymer synthetic material, whereby the effective working length of the string may be lengthened at desired times as the working length becomes shortened during use.
Another object of the present invention is to provide an improved mowing apparatus which is simple and compact in construction and less troublesome in use.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
For attaining the above objects, the apparatus according to the present invention includes an output axis rotatably mounted at one end of a supporting means and connected to an electric motor or a transmission driven by a gasoline-powered engine or the like. A rotary disk-like casing is detachably secured to the output axis for rotation therewith in a cutting plane. The casing consists of upper and lower disk portions coaxially disposed on the output axis and housing therebetween a supply of cutting string wound in the form of a hollow disk. A fastening portion is detachably fixed to the output axis for tightly fastening the upper and lower disk portions together about the cutting string. The upper disk portion is provided at its circumference with a depending circular wall, the inner diameter of which is arranged to be larger than the outer diameter of the supply of the cutting string. The supply of string is flatly coiled and each coil is radially interlinked with an adjacent core in a manner that the free end can unwind without disjoining of the coiled supply. The string extends outwardly through a guide port provided in the wall of the casing to form a cutting flail having an effective working length. The string is made of a high polymer synthetic material which is flexible and yielding to the extent that it is substantially incapable of causing damage or injury when impacting against persons or animals.
In one embodiment of the present invention, a single supply of cutting string in the form of a hollow disk is provided in a rotary casing in coaxial alignment with an output axis. Alternatively, two coiled cutting strings may be supplied in a rotary casing to provide two cutting flails extending from opposite sides of the periphery of the casing.
The apparatus of the present invention contains neither spools for winding the cutting string thereon nor devices for locking and releasing the spools, and therefore is simple and compact in construction. In one embodiment, the adjacent coils of the coiled supply of the cutting string is radially and partially interconnected by the use of various fastening means such as ultrasonic bonding, adhesive agents, film sheet backing, and injection molding so as to prevent the case from loosening, except for the case in which an additional length is pulled out.